<?php
/**
 * Plugin Name: AJO One-Click Cache Cleaner
 * Plugin URI: https://alijonline.com/
 * Description: A lightweight page caching plugin with a one-click admin bar cleaner and automatic cache purging on post updates.
 * Text Domain: ajo-one-click-cache-cleaner
 * License: GPL-2.0-or-later
 * Version: 1.0
 * Author: Ali J Online
 * Author URL: https://alijonline.com/
 */

// Exit if accessed directly (Security standard)
if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

/**
 * Define Cache Directory path
 */
function ajo_get_cache_dir() {
    return WP_CONTENT_DIR . '/cache/ajo-one-click-cache/';
}

/* ==========================================================================
 * 1. CACHING ENGINE
 * ========================================================================== */

// Start Output Buffering
add_action( 'template_redirect', 'ajo_start_caching', 0 );
function ajo_start_caching() {
    // Bypass cache if user is logged in, during search, on 404, or if there's a POST/GET request
    if ( is_user_logged_in() || is_search() || is_404() || $_SERVER['REQUEST_METHOD'] === 'POST' || ! empty( $_GET ) ) {
        return;
    }

    $cache_file = ajo_get_cache_filepath();
    
    // Serve cached file if it exists and is less than 24 hours old
    if ( file_exists( $cache_file ) && ( time() - filemtime( $cache_file ) ) < 86400 ) {
        readfile( $cache_file );
        echo "\n<!-- Cached by AJO One-Click Cache Cleaner -->";
        exit;
    }

    // Start capturing the HTML output
    ob_start( 'ajo_end_caching' );
}

// Save Output Buffer to file
function ajo_end_caching( $buffer ) {
    // Do not cache very small outputs or errors
    if ( strlen( $buffer ) < 255 ) {
        return $buffer;
    }

    $cache_dir  = ajo_get_cache_dir();
    $cache_file = ajo_get_cache_filepath();

    // Create cache directory if it doesn't exist
    if ( ! file_exists( $cache_dir ) ) {
        wp_mkdir_p( $cache_dir );
    }

    // Save the file securely
    if ( is_writable( $cache_dir ) || is_writable( dirname( $cache_dir ) ) ) {
        file_put_contents( $cache_file, $buffer );
    }

    return $buffer;
}

// Generate a unique file path for the current URL
function ajo_get_cache_filepath() {
    $protocol = isset( $_SERVER['HTTPS'] ) && $_SERVER['HTTPS'] === 'on' ? 'https' : 'http';
    $url      = $protocol . '://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
    $hash     = md5( $url );
    return ajo_get_cache_dir() . $hash . '.html';
}

/* ==========================================================================
 * 2. CACHE CLEARING LOGIC
 * ========================================================================== */

// The core function to empty the cache directory
function ajo_clear_all_cache() {
    $cache_dir = ajo_get_cache_dir();

    if ( ! is_dir( $cache_dir ) ) {
        return;
    }

    // Recursively delete files and folders inside the specific cache directory safely
    $files = new RecursiveIteratorIterator(
        new RecursiveDirectoryIterator( $cache_dir, RecursiveDirectoryIterator::SKIP_DOTS ),
        RecursiveIteratorIterator::CHILD_FIRST
    );

    foreach ( $files as $fileinfo ) {
        $todo = ( $fileinfo->isDir() ? 'rmdir' : 'unlink' );
        @$todo( $fileinfo->getRealPath() );
    }
}

/* ==========================================================================
 * 3. ADMIN BAR BUTTON (One-Click Cleaner)
 * ========================================================================== */

// Add the button to the WordPress Top Admin Bar
add_action( 'admin_bar_menu', 'ajo_add_admin_bar_button', 100 );
function ajo_add_admin_bar_button( $admin_bar ) {
    // Only show to administrators
    if ( ! current_user_can( 'manage_options' ) ) {
        return;
    }

    $nonce = wp_create_nonce( 'ajo_clear_cache_nonce' );
    $url   = admin_url( 'admin-post.php?action=ajo_clear_cache&_wpnonce=' . $nonce );

    $admin_bar->add_node( [
        'id'    => 'ajo-clear-cache',
        'title' => 'AJO One-Click Cache Cleaner',
        'href'  => esc_url( $url ),
        'meta'  => [
            'class' => 'ajo-clear-cache-btn',
            'title' => 'Clear all cached pages'
        ]
    ] );
}

// Handle the click action
add_action( 'admin_post_ajo_clear_cache', 'ajo_handle_clear_cache' );
function ajo_handle_clear_cache() {
    // Security checks: verify capability and nonce
    if ( ! current_user_can( 'manage_options' ) ) {
        wp_die( esc_html__( 'You do not have permission to perform this action.', 'ajo-one-click-cache-cleaner' ) );
    }
    check_admin_referer( 'ajo_clear_cache_nonce' );

    // Clear the cache
    ajo_clear_all_cache();

    // Safely redirect back to where the user clicked the button
    $referer = wp_get_referer();
    $redirect_url = $referer ? remove_query_arg( 'ajo_cleared', $referer ) : admin_url();
    $redirect_url = add_query_arg( 'ajo_cleared', '1', $redirect_url );
    
    wp_safe_redirect( esc_url_raw( $redirect_url ) );
    exit;
}

// Show a success message in the admin panel after clearing
add_action( 'admin_notices', 'ajo_admin_notice' );
function ajo_admin_notice() {
    if ( isset( $_GET['ajo_cleared'] ) && $_GET['ajo_cleared'] === '1' ) {
        echo '<div class="notice notice-success is-dismissible"><p>' . esc_html__( 'All cache purged successfully!', 'ajo-one-click-cache-cleaner' ) . '</p></div>';
    }
}

/* ==========================================================================
 * 4. AUTOMATIC CACHE CLEARING
 * ========================================================================== */

// Clear cache automatically when a post/page is created or updated
add_action( 'save_post', 'ajo_auto_clear_cache_on_save', 10, 3 );
function ajo_auto_clear_cache_on_save( $post_id, $post, $update ) {
    // Ignore autosaves, revisions, and bulk edits to prevent performance hits
    if ( wp_is_post_revision( $post_id ) || wp_is_post_autosave( $post_id ) || defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
        return;
    }

    // Check if the user has permission to edit the post
    if ( ! current_user_can( 'edit_post', $post_id ) ) {
        return;
    }

    // Fire the purge function
    ajo_clear_all_cache();
}